some suggestions for new locations
The mall - might have new enemies, a lot of loot but is dangerous so high risk high reward, stores that has items that can't be found anywhere else, multiple floors
Camping site/survivor site - safe, people who we can trade with and be friends with, can also be a save point maybe
Corrupted town - overrun with new enemies that might look like the people from the camping site but has some kind of dark(or any other color) goo attached onto their bodies, and they could have goo traps to trap the player kinda like the plant enemy, the houses might have rare items that can't be found anywhere else, and maybe you could have an item "jar of goo" that you can trade, craft, or do stuff with
The lake - relatively safe, but still has enemies that are specific to the place. The player character could be able to clean themself and dip in the lake, but the lake could have different color water and the different colored water could have an enemy in the water